Base oil blends having unexpectedly low brookfield dynamic viscosity and lubricant compositions therefrom

ABSTRACT

A base oil having an unexpectedly low dynamic viscosity as measured by ASTM D5133 test method comprises a blend of about 65 to 97.5 wt % of a paraffinic oil having a VI of 130 or greater, a Kv@100° C. of about 3.8 cSt or greater and a pour point of −15° C. or less and an ester of lubricating viscosity of from about 35 to about 2.5 wt %. The base oil is further characterized as free of added viscosity modifiers.

This application claims the benefit of U.S. Provisional Application No. 60/774,366 filed Feb. 17, 2006.

Field of Invention

This invention relates to base oil blends for functional fluids, especially hydraulic fluids, that have an unexpectedly low dynamic viscosity. This invention also relates to lubricant composition or functional fluids comprising these base oil blends.

BACKGROUND OF THE INVENTION

Hydraulic equipment owners require their equipment to operate effectively over a wide temperature range. For example, cargo handling systems aboard cargo ships must be able to operate regardless of the prevailing climate, which can range from tropical to artic conditions. Consequently, hydraulic oils have been developed which have good low-temperature flow properties for service under severe cold climatic conditions and which provide good performance under hot climatic conditions.

In order to achieve the desired wide temperature working ranges, hydraulic fluids are commonly formulated in two ways. The first way involves using mixtures of solvent-refined paraffinic base oils and solvent refined naphthenic base oils with added viscosity modifier and pour point depressant. The second way involves using a poly alpha olefin base oil (PAO, Group IV base stock).

The first method requires a more complex formulation approach but is generally preferred because it is more cost effective than the second way, which requires an expensive special PAO base stock. However, the viscosity index modifiers employed in the first technique are subject to shear in service, thus causing a degradation in performance.

A base stock (as opposed to a base oil and a functional fluid) is defined as a hydrocarbon stream produced by a single manufacturer to the same specification (independent of feed source) and that is characterized by a unique formula, product identification number, or both. Base stocks may be manufactured using a variety of different processes including, but not limited to, distillation, solvent refining, hydrogen processing, oligomerization, esterification and rerefining. Rerefining stock shall be substantially free from materials introduced through manufacturing, contamination or previous uses. A base oil is the base stock or blend of base stocks used in formulated lubricant or functional fluid compositions. A lubricant composition may be a base stock, a base oil, either alone or mixed with other stocks, oils or functional additives.

An object of the present invention is to provide functional fluids, and especially hydraulic fluids, that exhibit good low temperature performance in the absence of an added viscosity modifier.

Another object of the present invention is to provide functional fluids, and especially hydraulic fluids, that employ a base oil other than a PAO.

These and other objects will become apparent from the description which follows.

SUMMARY OF THE INVENTION

Broadly stated, the present invention encompasses base stocks, base oils and functional fluid compositions that have the surprising and unexpected combustion of properties of a high viscosity index (VI) and good low temperature performance in the absence of an added viscosity index modifier.

In a preferred embodiment base stocks and base oils are provided comprising:

-   (a) from about 65 to about 97.5 wt %, based on the base stock or     base oil, of an oil having a VI of 130 or greater, a Kv at 100° C.     of 3.8 cSt or greater and a pour point of −15° C. or lower; and -   (b) from about 2.5 to about 35 wt %, based on the base stock or base     oil, of an ester of lubricating viscosity.

BRIEF DESCRIPTION OF THE INVENTION

FIGS. 1 to 3 are graphs showing the improved dynamic viscosity of lubricant compositions of the invention as compared to compositions based on polyalpha olefins when measured by ASTM D5133.

DETAILED DESCRIPTION OF THE INVENTION

The base stocks or base oils of the present invention have both a high viscosity index and exhibit good low temperature performance as evidenced by their dynamic viscosity as measured by ASTM D5133. Indeed, the base stocks and base oils of the invention do not require added viscosity modifiers to achieve their low temperature performance properties.

These base stocks and base oils are a blend of a paraffinic oil having a VI of about 130 or greater a Kv at 100° C. of about 3.8 cSt or greater and a pour point of about −15° C. or lower, and an ester of lubricating viscosity.

Preferably, the paraffinic oil will have a VI of from about 130 to about 160 and more preferably from about 140 to 150; a Kv at 100° C. of from about 3 cSt to about 10 cSt and more preferably about 3.8 cSt to about 6.8 cSt; and a pour point (ASTM D97) of from about 0° C. to about −30° C. and more preferably from about −15° C. to about −25° C.

Process:

The paraffinic oils recited herein are made from waxy feedstocks to meet the requirement of a Group III base stock while at the same time having excellent properties such as high VI and low temperature performance.

The waxy feedstock used in these processes may derive from natural or mineral or synthetic sources. The feed to this process may have a waxy paraffins content of at least 50% by weight, preferably at least 70% by weight, and more preferably at least 80% by weight. Preferred synthetic waxy feedstocks generally have waxy paraffins content by weight of at least 90 wt %, often at least 95 wt %, and in some instances at least 97 wt %. In addition, the waxy feed stock used in these processes to make the base stocks and base oils recited herein may comprise one or more individual natural, mineral, or synthetic waxy feedstocks, or any mixture thereof.

In addition, feedstocks to these processes may be either taken from conventional mineral oils, or synthetic processes. For example, synthetic processes may include GTL (gas-to-liquids) or processes such as the Kolbel-Englehardt process and the FT (Fischer-Tropsch) process in which waxy hydrocarbons are catalytically produced from CO and hydrogen. Many of the preferred feedstocks are characterized as having predominantly saturated (paraffinic) compositions.

In more detail, the feedstock used in the process of the invention are wax-containing feeds that boil in the lubricating oil range, typically having a 10% distillation point greater than 650° F. (343° C.), measured by ASTM D86 or ASTM 2887, and are derived from mineral or synthetic sources. The wax content of the feedstock is at least about 50 wt %, based on feedstock and can range up to 100 wt % wax. The wax content of a feed may be determined by nuclear magnetic resonance spectroscopy (ASTM D5292), by correlative ndM methods (ASTM D3238) or by solvent means (ASTM D3235). The waxy feeds may be derived from a number of sources such as natural or mineral or synthetic. In particular, waxy feeds may include, for example, oils derived from solvent refining processes such as raffinates, partially solvent dewaxed oils, deasphalted oils, distillates, vacuum gas oils, coker gas oils, slack waxes, foots oils and the like, and Fischer-Tropsch waxes. Preferred feeds are slack waxes and Fischer-Tropsch waxes. Slack waxes are typically derived from hydrocarbon feeds by solvent or propane dewaxing. Slack waxes contain some residual oil and are typically deoiled. Foots oils are derived from deoiled slack waxes. The Fischer-Tropsch synthetic process prepares Fischer-Tropsch waxes. Non-limiting examples of suitable waxy feedstocks include Paraflint 80 (a hydrogenated Fischer-Tropsch wax) and Shell MDS Waxy Raffinate (a hydrogenated and partially isomerized middle distillate synthesis waxy raffinate).

Feedstocks may have high contents of nitrogen- and sulfur-contaminants. Feeds containing up to 0.2 wt % of nitrogen, based on feed and up to 3.0 wt % of sulfur can be processed in the present process. Feeds having a high wax content typically have high viscosity indexes of up to 200 or more. Sulfur and nitrogen contents may be measured by standard ASTM methods D5453 and D4629, respectively.

For feeds derived from solvent extraction, the high boiling petroleum fractions from atmospheric distillation are sent to a vacuum distillation unit, and the distillation fractions from this unit are solvent extracted. The residue from vacuum distillation may be deasphalted. The solvent extraction process selectively is dissolves the aromatic components in an extract phase while leaving the more paraffinic components in a raffinate phase. Naphthenes are distributed between the extract and raffinate phases. Typical solvents for solvent extraction include phenol, furfural and N-methyl pyrrolidone. By controlling the solvent to oil ratio, extraction temperature and method of contacting distillate to be extracted with solvent, one can control the degree of separation between the extract and raffinate phases.

Hydrotreating:

For hydrotreating, the catalysts are those effective for hydrotreating such as catalysts containing Group 6 metals (based on the IUPAC Periodic Table format having Groups from 1 to 18), Groups 8-10 metals, and mixtures thereof. Preferred metals include nickel, tungsten, molybdenum, cobalt and mixtures thereof. These metals or mixtures of metals are typically present as oxides or sulfides on refractory metal oxide supports. The mixture of metals may also be present as bulk metal catalysts wherein the amount of metal is 30 wt % or greater, based on catalyst. Suitable metal oxide supports include oxides such as silica, alumina, silica-aluminas or titania, preferably alumina. Preferred aluminas are porous aluminas such as gamma or beta. The amount of metals, either individually or in mixtures, ranges from about 0.5 to 35 wt %, based on the catalyst. In the case of preferred mixtures of groups 9-10 metals with group 6 metals, the groups 9-10 metals are present in amounts of from 0.5 to 5 wt %, based on catalyst and the group 6 metals are present in amounts of from 5 to 30 wt %. The amounts of metals may be measured by atomic absorption spectro-scopy, inductively coupled plasma-atomic emission spectrometry or other methods specified by ASTM for individual metals.

The acidity of metal oxide supports can be controlled by adding promoters and/or dopants, or by controlling the nature of the metal oxide support, e.g., by controlling the amount of silica incorporated into a silica-alumina support. Examples of promoters and/or dopants include halogen, especially fluorine, phosphorus, boron, yttria, rare-earth oxides and magnesia. Promoters such as halogens generally increase the acidity of metal oxide supports while mildly basic dopants such as yttria or magnesia tend to decrease the acidity of such supports.

Hydrotreating conditions include temperatures of from 150 to 400° C., preferably 200 to 350° C., a hydrogen partial pressure of from 1480 to 20786 kPa (200 to 3000 psig), preferably 2859 to 13891 kPa (400 to 2000 psig), a space velocity of from 0.1 to 10 liquid hourly space velocity (LHSV), preferably 0.1 to 5 LHSV, and a hydrogen to feed ratio of from 89 to 1780 m.sup.3/m.sup.3 (500 to 10000 scf/B), preferably 178 to 890 m.sup.3/m.sup.3.

Hydrotreating reduces the amount of nitrogen- and sulfur-containing contaminants to levels which will not unacceptably affect the dewaxing catalyst in the subsequent dewaxing step. Also, there may be certain polynuclear aromatic species which will pass through the present mild hydrotreating step. These contaminants, if present, will be removed in a subsequent hydrofinishing step.

During hydrotreating, less than 5 wt % of the feedstock, preferably less than 3 wt %, more preferably less than 2 wt %, is converted to 650° F. (343° C.) minus products to produce a hydrotreated feedstock whose VI increase is less than 4, preferably less than 3, more preferably less than 2 greater than the VI of the feedstock. The high wax contents of the present feeds results in minimal VI increase during the hydrotreating step.

The hydrotreated feedstock may be passed directly to the dewaxing step or preferably, stripped to remove gaseous contaminants such as hydrogen sulfide and ammonia prior to dewaxing. Stripping can be by conventional means such as flash drums or fractionators.

Dewaxing Catalyst:

The dewaxing catalyst may be either crystalline or amorphous.

Crystalline materials are molecular sieves that contain at least one 10 or 12 ring channel and may be based on aluminosilicates (zeolites) or on silicoalumino-phosphates (SAPOs). Zeolites used for oxygenate treatment may contain at least one 10 or 12 channel. Examples of such zeolites include ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, ferrierite, ITQ-13, MCM-68 and MCM-71. Examples of aluminophosphates containing at least one 10 ring channel include ECR-42. Examples of molecular sieves containing 12 ring channels include zeolite beta, and MCM-68. The molecular sieves are described in U.S. Pat. Nos. 5,246,566, 5,282,958, 4,975,177, 4,397,827, 4,585,747, 5,075,269 and 4,440,871. MCM-68 is described in U.S. Pat. No. 6,310,265. MCM-71 and ITQ- 13 are described in PCT published applications WO 0242207 and WO 0078677. ECR-42 is disclosed in U.S. Pat. No. 6,303,534. Preferred catalysts include ZSM-48, ZSM-22 and ZSM-23. Especially preferred is ZSM-48. The molecular sieves are preferably in the hydrogen form. Reduction can occur in situ during the dewaxing step itself or can occur ex situ in another vessel.

Amorphous dewaxing catalysts include alumina, fluorided alumina, silica-alumina, fluorided silica-alumina and silica-alumina doped with Group 3 metals. Such catalysts are described for example in U.S. Pat. Nos. 4,900,707 and 6,383,366.

The dewaxing catalysts are bifunctional, i.e., they are loaded with a metal hydrogenation component, which is at least one Group 6 metal, at least one Group 8- 10 metal, or mixtures thereof. Preferred metals are Groups 9- 10 metals. Especially preferred are Groups 9-10 noble metals such as Pt, Pd or mixtures thereof (based on the IUPAC Periodic Table format having Groups from 1 to 18). These metals are loaded at the rate of 0.1 to 30 wt %, based on catalyst. Catalyst preparation and metal loading methods are described for example in U.S. Pat. No. 6,294,077, and include for example ion exchange and impregnation using decomposable metal salts. Metal dispersion techniques and catalyst particle size control are described in U.S. Pat. No. 5,282,958. Catalysts with small particle size and well dispersed metal are preferred.

The molecular sieves are typically composited with binder materials which are resistant to high temperatures which may be employed under dewaxing conditions to form a finished dewaxing catalyst or may be binderless (self bound). The binder materials are usually inorganic oxides such as silica, alumina, silica-aluminas, binary combinations of silicas with other metal oxides such as titania, magnesia, thoria, zirconia and the like and tertiary combinations of these oxides such as silica-alumina-thoria and silica-alumina magnesia. The amount of molecular sieve in the finished dewaxing catalyst is from 10 to 100, preferably 35 to 100 wt %, based on catalyst. Such catalysts are formed by methods such spray drying, extrusion and the like. The dewaxing catalyst may be used in the sulfided or unsulfided form, and is preferably in the sulfided form.

Dewaxing conditions include temperatures of from 250-400° C., preferably 275-350° C., pressures of from 791 to 20786 kPa (100 to 3000 psig), preferably 1480 to 17339 kPa (200 to 2500 psig), liquid hourly space velocities of from 0.1 to 10 hr.sup.−1, preferably 0.1 to 5 hr.sup.−1 and hydrogen treat gas rates from 45 to 1780 m.sup.3/m.sup.3 (250 to 10000 scf/B), preferably 89 to 890 m.sup.3/m.sup.3 (500 to 5000 scf/B).

Hydrofinishing:

At least a portion of the product from dewaxing is passed directly to a hydrofinishing step without disengagement. It is preferred to hydrofinish the product resulting from dewaxing in order to adjust product qualities to desired specifications. Hydrofinishing is a form of mild hydrotreating directed to saturating any lube range olefins and residual aromatics as well as to removing any remaining heteroatoms and color bodies. The post dewaxing hydrofinishing is usually carried out in cascade with the dewaxing step. Generally the hydro-finishing will be carried out at temperatures from about 150° C. to 350° C., preferably 180° C. to 250° C. Total pressures are typically from 2859 to 20786 kPa (about 400 to 3000 psig). Liquid hourly space velocity is typically from 0.1 to 5 LHSV (hr.sup.−1), preferably 0.5 to 3 hr.sup.−1 and hydrogen treat gas rates of from 44.5 to 1780 m.sup.3/m.sup.3 (250 to 10,000 scf/B).

Hydrofinishing catalysts are those containing Group 6 metals (based on the IUPAC Periodic Table format having Groups from 1 to 18), Groups 8-10 metals, and mixtures thereof. Preferred metals include at least one noble metal having a strong hydrogenation function, especially platinum, palladium and mixtures thereof. The mixture of metals may also be present as bulk metal catalysts wherein the amount of metal is 30 wt % or greater based on catalyst. Suitable metal oxide supports include low acidic oxides such as silica, alumina, silica-aluminas or titania, preferably alumina. The preferred hydrofinishing catalysts for aromatics saturation will comprise at least one metal having relatively strong hydrogenation function on a porous support. Typical support materials include amorphous or crystalline oxide materials such as alumina, silica, and silica-alumina. The metal content of the catalyst is often as high as about 20 wt % for non-noble metals. Noble metals are usually present in amounts no greater than about 1 wt %.

The hydrofinishing catalyst is preferably a mesoporous material belonging to the M41S class or family of catalysts. The M41S family of catalysts are mesoporous materials having high silica contents whose preparation is further described in J. Amer. Chem. Soc., 1992, 114, 10834. Examples included MCM-41, MCM-48 and MCM-50. Mesoporous refers to catalysts having pore sizes from 15 to 100 .ANG. A preferred member of this class is MCM-41 whose preparation is described in U.S. Pat. No. 5,098,684. MCM-41 is an inorganic, porous, non-layered phase having a hexagonal arrangement of uniformly-sized pores. The physical structure of MCM-41 is like a bundle of straws wherein the opening of the straws (the cell diameter of the pores) ranges from 15 to 100 Angstroms. MCM-48 has a cubic symmetry and is described for example is U.S. Pat. No. 5,198,203 whereas MCM-50 has a lamellar structure. MCM-41 can be made with different size pore openings in the mesoporous range. The mesoporous materials may bear a metal hydrogenation component which is at least one of Group 8, Group 9 or Group 10 metals. Preferred are noble metals, especially Group 10 noble metals, most preferably Pt, Pd or mixtures thereof.

Generally the hydrofinishing will be carried out at temperatures from about 150° C. to 350° C., preferably 180° C. to 250° C. Total pressures are typically from 2859 to 20786 kPa (about 400 to 3000 psig). Liquid hourly space velocity is typically from 0.1 to 5 LHSV (hr.sup.−1), preferably 0.5 to 3 hr.sup.−1 and hydrogen treat gas rates of from 44.5 to 1780 m.sup.3/m.sup.3 (250 to 10,000 scf/B).

The ester of lubricating viscosity will typically have a Kv at 100° C. in the range of about 2.5 cSt to about 8.5 cSt. Typically the Kv at 40° C. will be from about 8 to about 92 cSt.

Typical properties are: Esterex A51 KV100 typical=2.73, KV 40=8.9 to 9.4 cSt, pour point=−54° C. Esterex A32 KV100=5.1 to 5.5 cSt, KV40=25.5−29.0 cSt, pour point=−54° C. Esterex P81 KV 100=8.2 cSt, KV 40=81−92 cSt, pour point−37° C.

In general, the paraffinic oils and the esters will be blended in the weight ratio of about 97.5:2.5 to about 65:35 and preferably about 95:5 to about 70:30.

Esters suitable for use in the present invention include those esters of dibasic acids with monoalkanols and the polyol esters of monocarboxcylic acids. Esters of the former type include, for example, the esters of dicarboxylic acids such as phthalic acid, succinic acid, adipic acid and the like with a variety of alcohols such as butyl, hexyl and dodecyl alcohol to mention a few.

Particularly useful synthetic esters are those which are obtained by reacting one or more polyhydric alcohols, preferably the hindered polyols (such as the neopentyl polyols, e.g., neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane, pentaerythritol and dipentaerythritol) with alkanoic acids containing at least about 4 carbon atoms such as C5 to C30 acids (such as saturated straight chain fatty acids including caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures thereof).

Suitable synthetic ester components include esters of trimethylol propane, trimethylol butane, trimethylol ethane, pentaerythritol and/or dipenta-rythritol with one or more monocarboxylic acids containing from about 5 to about 10 carbon atoms. Such esters are widely available commercially, for example, the Esterex™ esters sold by ExxonMobil Chemical Company.

Other esters may included natural esters and their derivatives, fully esterified or partially esterified, optionally with free hydroxyl or carboxyl groups. Such ester may included glycerides, natural and/or modified vegetable oils, derivatives of fatty acids or fatty alcohols.

Performance Additives:

The instant invention can be used with additional lubricant components in effective amounts in lubricant compositions, such as for example polar and/or non-polar lubricant base oils, and performance additives such as for example, but not limited to, metallic and ashless oxidation inhibitors, metallic and ashless dispersants, metallic and ashless detergents, corrosion and rust inhibitors, metal deactivators, anti-wear agents (metallic and non-metallic, low-ash, phosphorus-containing and non-phosphorus, sulfur-containing and non-sulfur types), extreme pressure additives (metallic and non-metallic, phosphorus-containing and non-phosphorus, sulfur-containing and non-sulfur types), anti-seizure agents, pour point depressants, wax modifiers, seal compatibility agents, friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, and others. For a review of many commonly used additives see Klamann in Lubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0, which also gives a good discussion of a number of the lubricant additives discussed mentioned below. Reference is also made “Lubricant Additives” by M. W. Ranney, published by Noyes Data Corporation of Parkridge, N.J. (1973). In particular, the base oils recited herein can show significant performance advantages with modern additives and/or additive systems, and additive packages that impart characteristics of low sulfur, low phosphorus, and/or low ash to formulated functional fluid.

Typical Additive Amounts:

When lubricating oil compositions contain one or more of the additives discussed above, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. Typical amounts of such additives useful in the present invention are shown in the Table 1 below. TABLE 1 Typical Amounts of Various Lubricant Components Approximate wt % Approximate wt % Compound (useful) (preferred) Detergent   0-6 0.01-4 Dispersant    0-20  0.1-8 Friction Reducer   0-5   0.01-1.5 Antioxidant 0.01-5 0.01-2 Corrosion Inhibitor 0.01-5   0.01-1.5 Anti-wear Additive 0.01-6 0.01-4 Pour Point Depressant   0-5 0.01-4 Demulsifier 0.001-3    0.01-1.5 Anti-foam Agent 0.001-3   0.001-1.5 Base Oil(s) Balance Balance

EXAMPLES

The properties of two paraffinic oils, Visom 4 and Visom 6 used to prepare a base oil of the invention are compared with the properties of two commercially available PAOs in Table 2. TABLE 2 Visom Visom PAO PAO PAO 4 6 4 6 100 Kv @ 100° C., cSt 4.0 6.6 4.1 5.8 105 (ASTM D445) VI 140 144 120 132 168 (ASTM D 2270) Pour Point, ° C. −18 −18 −54 −54 −21 (ASTM D5950)

Each of the oils were blended with an ester, the amounts of which are shown in Table 3. Also, each of the blends included the same lubricant additive in the same amounts. The properties of the fully formulated oils of the invention and the comparative oils are also shown in Table 3. TABLE 3 Comparative 1 Example 1 Comparative 2 Example 2 Example 3 Components wt % PAO 4 66.64 Esterex ™ 51 30 30 PAO 6 66.86 Esterex ™ 32 25 25 Visom 6 63.46 64.46 PAO 100 3 Visom 4 66.64 8 16 Synesstic 5 10 Esterex ™ P81 6 Pour Point 0.2 0.2 0.2 Depressant Additives Balance Balance Balance Balance Balance Properties Kv @ 40° C. (cSt) 14.72 14.35 32.83 31.35 31.9 Kv @ 100° C. (cSt) 3.637 3.5 = 681 6.26 6.144 6.1 VI 135 149 144 148 142 Pour Point (ASTM 97) <−60 −51 −54 −42 −42 Brookfield −18° C. 230 230 910 980 1000 (D 2983) Brookfield −40° C. 1,710 2,240 9,360 15,800 18,020 (D 2983)

FIG. 1 graphically compares the dynamic viscosity of the oil of Example 1 of the invention with Comparative Oil 1, while FIG. 2 compares the oil of Examples 2 and 3 of the invention with Comparative Oil 2 using the ASTM D5133 test method. 

1. A base stock or base oil comprising: (a) from about 65 to about 97.5 wt %, based on the weight of the base stock or base oil of a paraffinic oil having a VI of 130 or greater, a Kv at 100° C. of about 3.8 cSt or greater and a pour point of −15° C. or less; and (b) from about 2.5 to about 35 wt %, based on the weight of the base stock or base oil of an ester of lubricating viscosity, wherein the base stock or base oil has good low temperature performance as evidenced by their dynamic viscosity as measured by ASTM D5133 test method.
 2. The base stock or base oil of claim 1 further characterized as free of added viscosity modifiers.
 3. The base stock or base oils of claim 2 wherein the paraffinic oil is produced by a process which comprises: (a) hydrotreating a feedstock having a wax content of about 60 wt % based on feedstock with a hydrotreating catalyst under effective hydrotreating conditions such that less than 5 wt % of the feedstock is converted to 650° F. (343° C.) minus products to produce a hydrotreated feedstock whose VI increase is less than 4 and greater than the VI of the feedstock; (b) stripping the hydrotreated feedstock to separate gaseous product from liquid product; (c) hydrodewaxing the liquid product with a dewaxing catalyst which is at least one of ZSM-48, ZSM-57, ZSM-23, ZSM-22, ZSM-35, ferrierite, ECR-42, ITQ-13, MCM-71, MCM-68, beta, fluorided alumina, silica-alumina or fluorided silica-alumina, under effective hydrodewaxing conditions wherein the dewaxing catalyst contains at least one Group 9 or Group 10 metal.
 4. A functional fluid composition comprising the base stock or base oil of claims 1 or 3 and at least one additive other than a viscosity modifier.
 5. A method of making a functional fluid having a high VI and good low temperature performance as evidenced by dynamic viscosity as measured by ASTM D5133 test method comprising: blending (i) from about 65 to about 97.5 wt %, based on the weight of the fluid, of a paraffinic oil prepared by: (a) hydrotreating a feedstock having a wax content of about 60 wt % based on feedstock with a hydrotreating catalyst under effective hydrotreating conditions such that less than 5 wt % of the feedstock is converted to 650° F. (343° C.) minus products to produce a hydrotreated feedstock whose VI increase is less than 4 and greater than the VI of the feedstock; (b) stripping the hydrotreated feedstock to separate gaseous product from liquid product; (c) hydrodewaxing the liquid product with a dewaxing catalyst which is at least one of ZSM-48, ZSM-57, ZSM-23, ZSM-22, ZSM-35, ferrierite, ECR-42, ITQ-13, MCM-71, MCM-68, beta, fluorided alumina, silica-alumina or fluorided silica-alumina, under effective hydrodewaxing conditions wherein the dewaxing catalyst contains at least one Group 9 or Group 10 metal, with (ii) from about 2.5 to about 35 wt %, based on the weight of the fluid, of an ester of lubricating viscosity.
 6. The method of claim 5 including incorporating at least one additive other than a viscosity modifier. 